Heating energy demand of non-residential buildings using updated Degree Days in Italy

The weather is one of the main factors to be considered for the building design because it represents the most important boundary condition affecting the dynamic behaviour of the building during its useful life. One of the most representative climatic indexes is the Degree-Day (DD). The close correlation that exists between DD and the building energy required is valid only if the assessment of the energy demand has been verified for the same updated database that led to the DD evaluation. The authors, identified the relationship between DD and winter energy performance, determining some simple correlations to derive a preliminary evaluation of building energy demands. At the same time the study is aimed at verifying the importance of the climatic data used in simulation models. The authors calculated Heating Degree Days (HDD) using different climate files developing different relationships and different feedback between the HDD and heating energy demand evaluating the reliability degree by the correlation coefficients (R2). For the extraction of these correlations, numerous dynamic simulations (13 building models, located in 15 Italian cities) on non-residential buildings characterized by high-energy performances and modelled on the Italian technical standard have been carried out. The high degree of correlation of each issued relationship, clearly prove that HDD is a good index for assessing the energy performance of a building.